U.S. Pat. No. 4,079,458 issued Mar. 14, 1978 to Rider et al discloses a bit map character generator in which character bit maps are stored in a reduced format to save memory space in a character font memory. FIGS. 2 and 3 show typical bit maps of a letter "A" in both normal portrait and normal landscape mode respectively. The traditional em square storage format is indicated by solid line 10, compared with a reduced storage format indicated by dashed line 12 of the type described in the Rider et al patent. Each bit within the character is represented in memory as a 1, and each bit outside the character within the rectangular boundary of the character is represented as a zero. As can be seen in FIGS. 2 and 3, the storage requirements for the characters can be considerably reduced by eliminating surrounding areas that would consist only of zeros. However, in reducing the format in this way, some information such as the location of the character baseline, the space between characters, and the number of words (a word is a group of 16 bits) in the bit map character representation have been lost. It is necessary to supply this information to a bit map character generator that employs the reduced format fonts. FIG. 4 is a simplified block diagram of a prior art character generator of the type shown in U.S. Pat. No. 4,079,458 employing the reduced format bit map fonts. The character generator includes a master processor 20 that receives print commands from an input device (not shown), such as a personal computer. The master processor 20 typically comprises a programmed microprocessor. A look-up table 22 contains font parameters such a character height, width, and font address, and font statistics such as the character alignment (.DELTA.x, .DELTA.y). .DELTA.x, .DELTA.y define the alignment of the lower left corner of the reduced format bit map with respect to the baseline location of where the character should be placed. The master processor 20 retrieves the character parameters and statistics from the look-up table 22 by addressing the look-up table with a character identifier (ID) such as ASCII code. The master processor 20 computes the x, y page location for the character, using the character statistics, and sends the height, width, font address, and the x, y page location of the character to a bit map character generator 24. The bit map character generator 24 employs the font address and the character height and width, to retrieve the character bit map from a font memory 26 and sends the bit map to a buffer memory 27 and from there to a marking engine (not shown). The buffer memory 27 may comprise a line or page buffer, depending on the design of the character generator.
Since the master processor 20 is a programmed microprocessor, each font parameter look-up takes a separate sequence of machine instructions, which consume processor time and limit the speed of character generation. It is therefore the object of the present invention to provide an improved character generator of the type employing a reduced font.